1. Field of the Invention
The present invention relates to a process for producing a translucent .beta.-SIALON sintered product.
2. Description of the Prior Art
.beta.-SIALON is composed of .beta.-type silicon nitride (Si.sub.3 N.sub.4) partly substituted at its Si-position and N-position by solid solution components of Al and O, respectively. Like a silicon nitride sintered product, the .beta.-SIALON sintered product has superior high temperature strength and thermal shock resistance and a small thermal expansion coefficient. Further, it exhibits not only oxidation resistance at a high temperature but also superior corrosion resistance against slags and molten metals. Thus, it is expected to be a superior new high temperature material.
Heretofore, the .beta.-SIALON sintered product has been produced by heating a mixture composed of a predetermined molar ratio of Si.sub.3 N.sub.4 --Al.sub.2 O.sub.3 --AlN or Si.sub.3 N.sub.4 --SiO.sub.2 --AlN at a high temperature by hot-pressing or by sintering. However, the sintered product thereby obtained does not have a translucency. There has been no attempt to make it translucent. If a translucent property is imparted in addition to the above-mentioned superior high temperature characteristics, the sintered product will be useful for application to an emission tube for a high pressure sodium lamp and as a high temperature window material or a window material for an infrared ray detector or as a substrate for IC.